Basicly a\n?b\n?c means match a followed by, perahps ? a newline \n followed by a b followed by, perahps ? a newline \n and a c

The m regex modifier (probably unneeded in my example) stands for multiline and the g one means globally ie all occurences are returned.

$count=()=$string=~/pattern/g idiom is used to count the occurences of pattern in $string infact $string=~/pattern/g with the g returns a list and the generic list () is provided and it's scalar value (ie the number of elements) is returned to the scalar $count

For shortness i put your example data into a doublequoted string using qq operator qq(abcdefab\ncdefa\nbcdef)

the rest is only print stuffs.

If you want to slurp a file into a string you can play with $/ aka input record separator, see perlvar and How do I read an entire file into a string?

L*

No it is not the time. If I output the string to a txt file it creates the file in a few seconds but when I open the file in a text editor it seems corrupt with characters displaying one on top of another.

Create a hex dump of the problematic file, and post a relevant part of it.

If you are on unix (Linux, BSD, Mac OS X), try the command od -tx1 -c filename.txt:

>find . -name '*.txt' -print -exec od -tx1 -c {} \;
./linux-file.txt
0000000  41  20  73  69  6d  70  6c  65  20  66  69  6c  65  20  67  6
+5
          A       s   i   m   p   l   e       f   i   l   e       g   
+e
0000020  6e  65  72  61  74  65  64  0a  6f  6e  20  4c  69  6e  75  7
+8
          n   e   r   a   t   e   d  \n   o   n       L   i   n   u   
+x
0000040  20  77  69  74  68  20  55  6e  69  78  0a  6c  69  6e  65  2
+0
              w   i   t   h       U   n   i   x  \n   l   i   n   e
0000060  65  6e  64  69  6e  67  73  2e  0a
          e   n   d   i   n   g   s   .  \n
0000071
./windows-file.txt
0000000  41  20  73  69  6d  70  6c  65  20  66  69  6c  65  20  67  6
+5
          A       s   i   m   p   l   e       f   i   l   e       g   
+e
0000020  6e  65  72  61  74  65  64  0d  0a  6f  6e  20  57  69  6e  6
+4
          n   e   r   a   t   e   d  \r  \n   o   n       W   i   n   
+d
0000040  6f  77  73  20  77  69  74  68  20  57  69  6e  64  6f  77  7
+3
          o   w   s       w   i   t   h       W   i   n   d   o   w   
+s
0000060  0d  0a  6c  69  6e  65  20  65  6e  64  69  6e  67  73  2e  0
+d
         \r  \n   l   i   n   e       e   n   d   i   n   g   s   .  \
+r
0000100  0a
         \n
0000101
./mac-file.txt
0000000  41  20  73  69  6d  70  6c  65  20  66  69  6c  65  20  67  6
+5
          A       s   i   m   p   l   e       f   i   l   e       g   
+e
0000020  6e  65  72  61  74  65  64  0d  6f  6e  20  57  69  6e  64  6
+f
          n   e   r   a   t   e   d  \r   o   n       W   i   n   d   
+o
0000040  77  73  20  77  69  74  68  20  4f  6c  64  20  4d  61  63  0
+d
          w   s       w   i   t   h       O   l   d       M   a   c  \
+r
0000060  6c  69  6e  65  20  65  6e  64  69  6e  67  73  2e  0d
          l   i   n   e       e   n   d   i   n   g   s   .  \r
0000076
[download]

A plain ASCII file should not contain any bytes outside the range 0x20 to 0x7E, except for 0x0D and / or 0x0A for newlines. Any other byte value below 0x20 is very fishy, as is 0x7F. Bytes from 0x80 to 0xFF should not appear in ASCII files, they may indicate some other encoding, like UTF-8 and various legacy encodings.

If (nearly) every second byte is 0x00, it is very likely a text file encoded in UTF-16 or UCS-2; if only every fourth byte is not 0x00, the file is probably encoded in UTF-32.

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

This "corrupt characters" sounds like what I suspect, that this file contains something other than ASCII. My experience in this regard is very limited, but other Monks know a lot about this. I highly suspect that a character set problem is causing the issue, but I don't know how to assist you further myself.

assuming you're really only looking for a short string, and given the size of your file, I would be tempted to only concatenate the new line with the last few nonspace characters from the previous line(s), and do the comparison every loop.